Someone asked me this question and I thought I'd pass it on to you guys. What are the most interesting NES prototypes discovered so far and why ?

- From those featured on the main site I'd say these got to be mentioned: Earthbound, Sunman, Bio Force Ape, but I'd like to hear about some other games you think are noteworthy for one reason or another.

Yeah, I went lurker, but I'm still breathing. Don't have much to add most of the time. Apparently I'm an old man now!

Thanks for finding that article on the wayback machine Skrybe, I forgot how ridiculous it article was. The bit with the diaper is probably the stupidest thing I've ever written. I don't know about brilliant, adaml, you're nuts. :) Rereading it, it wasn't as bad as I thought it would be, but in spots, jesus.

Ballzy, I almost spoke up when that Rick and Morty shit went down, you know what I'm talking about. See, lurking, everywhere. I almost feel guilty not saying anything now :P

The protos I liked the much as probably Airball, Secret Ties and Time Diver Eon Man (tough it was kinda released in Eurasia and I still have my copy from the '90-ies).

As for prototypes, that are not discovered yet the one that I would love to play one day is probably Erik The Viking by Eurocom Developments.
Recently I've digged the sound driver of that game and it turned out that by setting a specific RAM address you can enable the driver to output a pitchperfect version for PAL versions.
Eurocom drivers were dual-region coded, which is pretty useful.

It got released, but I'll throw in the prototype of the Western Super Mario Bros. 2 that was kind of a halfway point between Yume Koujou Doki Doki Panic and the released SMB2 with its unique take on the classic Mario 1-2 underground music, and how it's a unique glimpse at a substantial localization work in progress for the banner series from what was at the time the undisputed most important company in the industry.

No way the NES could've handled WHAT STRENGTH! BUT DON'T FORGET THERE ARE GUYS LIKE YOU ALL OVER THE WORLD. :P
(then again, Sunsoft managed to put a surprising amount of voice in Mito Kouman, even if they had to compress it to almost ear-piercing low quality to make it fit)